Somatostatin and certain analogues of somatostatin have been observed inhibit gastric acid secretion. U.S. Pat. No. 4,061,626 discloses the activity of somatostatin, D-Lys.sup.4 -SRIF and D-Ala.sup.2, D-Lys.sup.4 -SRIF as gastric acid secretion inhibitors as well as inhibitors of growth hormone, glucagon and insulin secretion. U.S. Pat. No. 4,062,816 discloses the activity of D-Ala.sup.5 -SRIF as an inhibitor of gastric acid secretion as well as an inhibitor of growth hormone secretion. Lippmann et al., Pharmac. Res. Comm., 8, 445 (1976) discloses gastric acid secretion inhibition by somatostatin and several analogues, noting that D-Lys.sup.9 -SRIF had no appreciable effect on gastric acid secretion at a dose as high as 2 .mu.m/Kg, s.c.